Two-way flasher and circuit control



June 6, 1944. E. R. KULKA I 2,350,403

TWO-WAY FLASHER AND CIRCUIT CONTROL Filed Feb. 10, 1941. 2 Sheets-Sheet l INVENTOR. Eugene H. Kullra Patented June 6, 1944 UNITED STATES PATENT OFFICE TWO-WAY FLASHER AND CIRCUIT CONTROL 2 Claims.

My invention relates to a new and improved circuit-controlling device, whereby current can be supplied intermittently to a single lamp or to a plurality of lamps. The invention includes, but is not limited to a two-way flasher in which current is supplied intermittently and successively to a pair of lamps of equal or of unequal wattage.

One of the objects of the invention is to provide a simple and eflicient device which can be made and assembled at low cost, and which can be used in combination with a single lamp, or a pair of lamps of equal or of unequal wattage.

Another object of the invention is to use a heating element of very low resistance and of large cross-section, which is connected in series in the circuit of a lamp.

Another object of the invention is to provide a device of this type which utilizes a helically wound bi-metallic strip, which .is flexible and which will permit substantial movement of the leg of the strip which carries contact points.

Another object of the invention is to operate a circuit-controlling switch by a bi-metallic member which is heated by a heating coil which is spaced from the bi-metallic member by an air gap. This heating coil is preferably bare, in order to secure maximum rapid heat radiation, but said heating coil or heating element may be covered with insulation.

Other objects of the invention will be set forth in the following description and drawings which illustrate a preferred embodiment thereof.

Fig. 1 is a circuit diagram of the device, showing certain of the mechanical parts of the device.

Fig. 2 is a top plan view of the helical bimetallic control member.

Fig. 3 is a plan of the heating coil of the device.

Fig. 4 is a top plan view of the device.

Fig. 5 is a sectional view on the line 55 of Fig. 4.

Fig. 6 is a sectional view on the line 6-6 of Fig. 4.

Fig. 7 is a view similar to Fig. 4, showing a pair of lamps, and the circuit connections.

The invention is shown as applied to a twoway flasher, as an example, but it is not restricted to a. two-way flasher.

While two-way flashers have heretofore been well known, they required the use of lamps of unequal wattage. The improved device makes it possible to use 1amps of equal or unequal wattage.

made of porcelain or other insulating material. This base has a through-and-through L-shaped slot, which has a lateral leg 2 and a longitudinal leg 3.

A bi-metallic helix 4 is located in the leg 2. This helix is made of two strips of metal of the usual type, said metal strips having unequal coeflicients of thermal expansion. The helix 4 has extensions 5 and 6. The tip of extension 5 is connected to base I by a suitable terminal member I. The extension 6 is freely movable up-anddown in the leg 3. For convenience, the device is described with reference to its position which is shown in the drawings, but of course the device may be held in any position. The extension 5 is provided with an upper contact 8 and a lower contact 9. These contacts are made of silver or any other suitable metal.

A metal plate I0 is rigidly connected by rivet I I to the top wall of base I. This metal plate III has a tapped bore, in which a screw I2 is adjustably mounted. The lower end of this screw I2 is provided with a contact point I4, which is also made of silver or any other suitable metal. A heating coil I5 is provided with end terminals I5 and I1. These end terminals are connected to base by terminal posts I64: and I111. The heating coil I5ls made of Nichrome or other suitable material and it is mounted upon a core I8 which is made of flexible asbestos or other suitable insulating material. This coil i5 is shown separated from the helix 4 in Fig. l, in order to illustrate the circuit more clearly.

A metal plate 20 is rigidly connected to the bottom wall of the base I by means of a rivet 2|, whose top end is exposed at the top wall of base I. This plate 20 has a contact point 22, which is made of silver or other suitable material.

The screw I2 is adjusted so that the contacts 8 and I4 touch each other, when the heating coil I5 and the helix 4 are at normal or room temperature.

It will be noted that since the wire of the heating coil I5 is not covered by insulation, the heat of the coil I5 is radiated directly to the helix 4, through the small air gap between the helix 4 and the heating coil I5. The bottom end of the rivet I I is connected by a suitable conductor 30 to the end terminal I1 of the heating coil I5, by means of terminal post Ila.

The junction post 23 is connected by wire 24 to one side of a suitable source of current, which I The device comprises a rigid base I, which is 65 may be direct or alternating. The extension 5 is connected by wire 25 to the other ide of said source of current.

Lamp 21 has one terminal thereof connected by wire 28 to junction post 23. The other terminal of lamp 21 is connected by wire 25 to the end terminal I6 of heating coil I5.

A lamp 21a has one terminal thereof connected by wire 3I to the junction post 23. The other terminal of lam 21a is connected by Wire 32 to plate 20. For convenience, it will be assumed that direct current is used and that the wire 24 is connected to the positive terminal of a source of direct current, and that the wire 25 is connected to the negative terminal of this sourc of direct current. Since the helix 4 and its extension 6 are made of resilient bi-metallic material, said extension 6 is normally biased so that the contacts 8 and I4 normally touch each other, and the contacts 9 and 22 are normally spaced from each other, when said helix 4 and its extension are at the temperature of the surrounding atmosphere.

Current will then flow from junction post 23 through wire 28, lamp 21, wire 26, heating coil I5, wire 30, top plate I0, screw I2, contact point I4, contact point 8, extension 5, helix 4, extension 5, to the negative side. Lamp 27a is then out of the circuit.

Coil I will be quickly heated above the temperature of the surrounding atmosphere, thus heating helix 4 by radiation, although heating coil I5 is insulated by an air gap from helix 4.

When helix 4 is heated, extension 6 will be deflected downwardly from the normal position to which said extension 6 is biased, until contact points I4 and 8 are separated, and contact points 9 and 22 touch each other.

Current will now flow from junction post 23, through wire 3|, lamp 21a, wire 32, bottom plate 20, contacts 22 and 9, extension 6, helix 4, extension 5, to the negative side. Lamp 21 and heating coil I5 will then be out of circuit.

The coil I5 and helix 4 will then cool, until extension 5 is moved back to the normal position shown in Fig, 1.

The lamps 21 and 21a ar thus alternately cut into and out of the circuit, and the device operates in substantially the same manner, if lamp 2'! and 21a are of equal or unequal wattage. This is an important feature of the invention, because commercial devices have heretofore required the use of lamps of unequal wattage. I

The respective lamps are alternately connected to the source of power by two parallel circuits,

only one of which includes the heating coil I5.

The metal which has the highest coeflicient of expansion when the temperature is raised, is on the upper surface of the helix 4.

By using a helix of substantial length, and locating the bare heating coil inwardly of the helix and close thereto, substantial advantages are secured. The helix can be made of suflicient length to provide a substantial movement of the extension 6, so that the device need not be made with great precision. Without limiting the invention to the practical example given, the length of extension 6 may be 1 inch, the

length of helix 4 may be /2 inch, and the length ,is from .008-.010 inch.

The heating coil is designed to operate the mally operated switch member, one end of which 7 is permanently connected to one side of the source of power. The other end of said member 6 is free. The respective shunt circuits of the lamps have control terminals I4 and 22, which contact alternately with the free end of said member 6.

For convenience, the lamp 21 will be designated as the first lamp, and the lamp 21a will be designated as the second lamp. Each of said lamps has a respective terminal thereof which is connected through the junction post 23, to one side of the source of electric power. The other terminal of the first lamp 2'! is connected through the heating coil I5 to the contact I4, which may be designated as the first contact. The other terminal of the second lamp 21a is connected directly to the contact 22, which may be designated as the second contact, in order to identify the elements which are specified in the claims. The helix 4 may be designated as heat-responsive means.

Whenever I refer to a slot in the base I, it is to be understood that a recess is equivalent. The extension 6 does not directly contact with the metal plate I0, but said extension 6 makes electrical connection with said plate I0 through the elements I4 and I2.

The device can be used as a single flasher by breaking the circuit between junction point 23 and the lamp 21a, or by merely omitting the lamp in the socket which receives the lamp 21a. When the heat-responsive device is in initial or normal circuit-closing position, the heating element I 5 is heated. so that the element 5 i moved to open the circuit. The heating element I5 may be of any shape or type. In prior flasher devices of this type, the heating element was in shunt with the lamp, or with one of the lamps. As an example, the resistance of an ordinary sixty watt lamp is 240 ohms, in an ordinary lighting circuit whose eiiective voltage is volts. In such case, the shunt heat.- ing resistance of the old device is from 2000-3000 ohms. Hence, if the lamps in a two-way flasher were of equal wattage, one of the lamps would not give any light. It was therefore necessary to use lamps of greatly different wattage. In my improved circuit, the heating resistance I5 is in series with one of the lamps. The resistance of coil I5 is very low, about 5-10 ohms, just enough to produce the heat required for operating the bi-metallic element. I can therefore use wire of large gauge in the heating element I5, thus allowing easy passage of the current which is required to operate the lamp at maximum brilliance. The size of the wire may be No. 33, Brown & Sharpe system, in order to operate a 60-watt lamp with maximum efficiency. The diameter of such wire is 0.0071 inch. In former devices, the heating coil was wrapped around a sheath of asbestos paper, which was wrapped around the bi -metallic element, in order to prevent a short-circuit of the fine heating wire which was used in the old device. This asbestos paper prevented the rapid transmission of heat. The fine wire. of the old device was'enamelled, and-its total thickness, including the enamel coatin was .0015 inch. Such thin wire is very olifiicult to manipulate. According to myinvention. the heating element is supported independently of the bi-metallic member, and said heating element is preferably bare, although it may have an enamel coating.

The lamp or lamps may be replaced by other electrical devices or resistances of any type. For example, the coil of a relay may be the load.

If the device is used in a two-way flasher, the resistance of the heating coil l preferably does not exceed substantially twenty-five per cent of the resistance of the associated lamp. If the device is used for other purposes, such as heating the thermostatic element which normally closes the circuit of the relay of a burglar-alarm, the period of heating which is required to actuate the thermostatic element to circuit-opening position may be relatively long, as about 30 seconds to 1 minute, for example.

I have described a preferred embodiment of the invention, but it is clear that numerous changes and omissions can be made without departing from its spirit.

Theoretically, the circuit of heating element I5 is broken, as soon as members l4 and 8 are separated, and before members 9 and 22 contact.

However, and as shown in Fig. 5, the leg 6 is normally slightly flexed, and members 8 and !4 therefore normally contact each other, under light pressure. The helix 4 is therefore heated above the required operating temperature, before members l4 and 8 are separated. The helix then has sufiicient accumulated heat to move extension 6, until elements 9 and 22 touch each other. The movement of extension 6 is very small.

I claim:

1. A two-way flasher comprising a base made of insulating material, a bi-metallic and heatresponsive helix which has a first extension and a second extension, the first extension being rigidly fixed to the base, said base having a slot in which the second extension is movably located so that the second extension can move relative to the base when the temperature of the helix is changed, the second extension being located between respective metal plates which are respectively rigidly secured to the base and which are insulated from each other, the second extension being movable to make electrical connection with either one of said metal plates, said second extension being biased to normally make electrical connection with one of said metal plates, a heating coil located inwardly of said helix and spaced from said helix, the ends of said heating coil being connected to the base at spaced points thereof, a conductor connecting one end of said heating coil to the metal plate with which said second extension is normally in electrical connection.

2. A two-way flasher comprising a support, a bi-metallic and heat responsive helix which is fixed to said support, said helix having a switchextension which is movable relative to said support, said extension being located between respective spaced metal contacts and being movable to touch either of said contacts, said extension being biased to normally touch one of said metal contacts, a heating element located inwardly of said helix and spaced from said helix and supported independently of said helix, one end of said heating coil being connected to the contact which said extension normally touches.

EUGENE R. KULKA. 

